NITRIC OXYDE. 43 



ammonia now combines with the disengaged nitrous 

 gas, and forms nitrous oxyd. 



To experience its effects in breathing it, put 

 about a gallon into a large bladder, or oiled silk 

 bag, having a tube attached to it, of three-fourths 

 of an inch in diameter. First, the common air 

 must be expelled from the lungs, before the tube 

 is received into the mouth, and the nostrils must be 

 accurately closed with the hand. It must then be 

 breathed backwards and forwards into the bag for 

 a few minutes. 



Nitric Oxyde is called also nitrous gas. This com- 

 pound of oxygen and nitrogen cannot be obtained by 

 direct combination, but by abstracting from nitric 

 acid a portion of its oxygen, leaving the remainder 

 in such proportion as to constitute nitric oxide. 



When pure, it is not acid, and is void of colour. 

 It is incapable of supporting the combustion of 

 most bodies; nevertheless, phosphorus and pyro- 

 phorus burn in it. Nitrous gas is made by putting 

 clippings or filings of copper into a retort with 

 nitric acid, diluted with thrice as much water ; red 

 fumes will be given out, if the gas is suffered to 

 escape into the air ; but if collected in the pneu- 

 matic apparatus, the gas is colourless. In this pro- 

 cess, the metal attracts the oxygen from the nitric 

 acid, and becomes oxydated ; the rest of the acid 

 being deprived of a great portion of its oxygen, can 

 no longer exist as acid ; it therefore expands, be- 

 comes aeriform, and appears as nitrous gas. 



When nitrous gas and oxygen gas are mixed to- 

 gether in a glass vessel, previously exhausted of air, 

 they instantly unite, and form a reddish coloured 

 gas, which has but half the volume of the two gases, 

 and which is highly acid. This new compound is 

 called nitrous acid gas. 



